Wikimedia Bugzilla is closed!

Specifically it fails when trying to insert text content between two inline aliens or after last inline alien inside its parent.

Exception:
Uncaught TypeError: Cannot read property 'start' of undefined ve.dm.TransactionProcessor.js:259
ve.dm.TransactionProcessor.processors.replace

// Set change markers on the parents of the affected nodes
for ( i = 0; i < selection.length; i++ ) {
	this.setChangeMarker(
		selection[i].parentOuterRange.start + this.adjustment,
		'content'
	);
}